CN107704653B - Cement-based material three-dimensional particle grouping and homogenizing throwing method - Google Patents
Cement-based material three-dimensional particle grouping and homogenizing throwing method Download PDFInfo
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Abstract
The invention discloses a cement-based material three-dimensional particle grouping and homogenizing throwing method, which comprises the following steps: establishing a cement particle library to be put in according to the drawn-up water cement ratio and the real cement particle size distribution, wherein the main parameters are that the particle size range of the cement particles is N groups and the number of the corresponding particles is N; calculating a particle size distribution characteristic value A of the cement particle library, and determining that the range of the particle size distribution characteristic value of the cement particles is Z; then randomly grouping all cement particles according to the particle size distribution range Z of the cement particles and putting the cement particles in a putting area; and (4) analyzing the particle distribution condition in the cement three-dimensional particle putting area. The method can realize continuous and uniform putting of the cement particles in the putting area, overcomes the problem that the cement particles with larger radius are too dense in some areas in the putting area due to the fact that the cement particles are put in from large to small in radius in the traditional putting method, and enables the cement particles to be uniformly distributed in the whole putting area.
Description
Technical Field
The invention relates to a numerical simulation method for random placement of cement-based material particles, in particular to a method for uniformly placing cement-based material three-dimensional particles in groups.
Background
Cement-based materials are one of the most widely used materials in civil engineering. However, since the cement-based material is a heterogeneous multi-phase multi-scale composite material, the microstructure thereof has randomness and complexity, the testing technology can only qualitatively represent the microstructure change of the cement-based material and the testing result is often limited by the precision of instruments and human errors. In addition, theoretical research usually requires more simplified conditions to better calculate the equivalent mechanical properties of the corresponding cement-based material model, such as limited conditions of less cement particle content. Therefore, the simulation of the complex microstructure of the cement-based material by the computer numerical value is becoming a hot point of international research, and the establishment of a reasonable cement-based material particle model is a premise for accurately realizing the simulation of the microstructure numerical value of the cement-based material and is a basis for developing the research on the macroscopic performance of the cement-based material under the condition of real cement particle size distribution. The reasonability of the random putting process and results can influence the reasonability of a microstructure model of the cement-based material in the numerical simulation process, so that the reliability of the numerical analysis result of the macroscopic property of the cement-based material is influenced.
The traditional cement-based material particle feeding method is mature in two-dimensional scale, and the real three-dimensional cement-based material particle feeding method is yet to be researched. At present, most of three-dimensional cement-based material particles are put in a method that the particle center positions are randomly generated by generating pseudo random numbers in the whole putting area according to the radius of all the particles from large to small, and whether the current positions of the particles are overlapped with the previous positions of the particles is checked before each putting. The method has the advantages of high feeding speed and capability of feeding all the particles with larger particle sizes. However, the method has the problem that the selected particle size is thrown from large to small, and when the throwing area is not changed, cement particles with larger radius are easily concentrated in certain areas, so that the particle distribution in the whole throwing area is uneven and not practical. The topological structure of the cement particle positions can influence the compressive strength of the cement system after hydration.
Therefore, the research is carried out aiming at the problem of putting the cement-based material three-dimensional particles in groups, a reasonable three-dimensional particle random putting method is provided, a cement-based material three-dimensional space model with uniform and reasonable particle distribution is established, a foundation is laid for realizing a cement-based material micro numerical simulation test, carrying out the research on the cement-based material macroscopic performance mechanism, and establishing the quantitative relation between the cement-based material microstructure and the macroscopic performance, and the method has very important academic significance and engineering application value.
Disclosure of Invention
The invention aims to provide a cement-based material three-dimensional particle grouping and homogenizing throwing method, which can realize the throwing of three-dimensional particles of cement systems with different water-cement ratio conditions and ensure that the three-dimensional particles are uniformly distributed in the whole throwing area, thereby constructing a cement-based material three-dimensional space model with the distribution conforming to the actual situation.
The invention realizes the aim through the following technical scheme:
a cement-based material three-dimensional particle grouping and homogenizing throwing method comprises the following steps:
step 1, generating a cement particle library to be put into a cement system
Determining the shape of cement particles to be spherical, obtaining the true particle size distribution PSD (particle SizeDistribution) of the cement particles, assuming the water-cement ratio w/c and the cement density to be rhocFixing the volume of the whole throwing area as v, the volume of the cement is 1/(1+ rho)c(w/c)). times.v. And then according to the PSD, the real number of each cement particle with different particle sizes can be determined, and a cement particle library to be put in is generated.
Step 2, obtaining a characteristic value A and a characteristic value range Z of the particle size distribution of the cement particles
According to the cement particle information obtained in the step 1, dividing the cement particles into three groups of particles with the radius larger than or equal to 1um, 4um and 8um according to the radius, and calculating according to a formula (1) to obtain a particle size distribution characteristic value A:
in the formula, A is a cement particle size distribution characteristic value, A1、A4、A8The percentage of the number of the particles with the cement particle radius of more than or equal to 1um, more than or equal to 4um and more than or equal to 8um in the total number of the particles is respectively. That is, the number of particles having a particle diameter of 3um or more, 9um or more, 17um or more is the percentage of the total number of particles. The particle size distribution characteristic a reflects the average fineness of the cement system. In the actual putting process, the closer the particles are to each other only when the number of a group of particles is largerA, the particle size distribution characteristic value range was therefore selected as Z ═ (a-0.4, a + 0.4). The number of the particles put in each group is assumed to be 100, and when the number of the particles put in the last group is less than 100, one particle is put in at a time.
And (3) selecting a proper group of particles to be put according to the cement particle size distribution characteristic value A and the characteristic value range Z obtained in the step (2). Because the number of the particles with smaller particle sizes in the cement system is thousands of times of the number of the particles with larger particle sizes, 100 particles are randomly selected from all the particles, and the 100 particles almost all consist of the particles with smaller particle sizes according to the statistical principle, can not represent the average fineness of the whole cement system, and can cause the uneven distribution of the particles in a cement particle putting area. Therefore, 1 group is randomly selected from the N groups of particles with different particle sizes by using a uniform random number, and after 1 particle in each group is selected, the particle is deleted from the group. Continuously selecting 100 times, wherein 100 particles are taken as a group, calculating the A value of the 100 particles, and if the A value is in the particle size distribution characteristic value range Z, randomly throwing the 100 particles in a throwing area; and if the value A is not in the particle size distribution characteristic value range Z, randomly selecting 100 particles again, and starting random feeding until the value A is in the particle size distribution characteristic value range Z.
Dividing a three-dimensional cement particle feeding area into a plurality of distribution analysis areas, analyzing the number of particles with different particle sizes in the material content distribution in each distribution analysis area, drawing a table, and listing the cement particle distribution in each distribution analysis area. The method is used for evaluating the quality of the grouped delivery of the three-dimensional cement particles.
The three-dimensional cement particles are spherical, and the particle size of the real cement particles is distributed in the range of 1-37 um.
The three-dimensional cement particle throwing area is 100um x 100 um.
The cement particle size and the cement particle radius are cubic pixels with the minimum unit size of 1um by 1um in a constructed throwing area, and in order to enable the spherical centers of all the cement particles to occupy just one pixel, the cement particle size is equal to the cement particle radius 2+ 1.
Cement granule particle size 3 ~ 30 um's cement granule plays the primary role to intensity, especially the particle size is in 3um more than or equal to, 9um, 17 um's of more than or equal to particle, thinks among the present research that particle size 3 ~ 30 um's cement granule plays the primary role in intensity
17-24 um particles. In the actual domestic cement production, the content of cement particles with the particle size of more than 17um is less. Therefore this patent selects 9um with the cement granule between 3um ~ 17um particle diameter, divides into three groups with the cement granule diameter distribution, and particle diameter more than or equal to 3um, the granule of more than or equal to 9um, the granule of particle diameter more than or equal to 17um acquire cement granule particle diameter distribution eigenvalue.
In the process of putting the cement particles in groups, after a proper group of particles are selected, the group of particles are put one by one. And randomly generating a sphere center coordinate in the putting area by the generated random number, and if the current particle is generated in the sphere center coordinate and has position overlap with the last generated particle, randomly selecting a sphere center position again until a proper position exists in the putting area.
The particle distribution analysis area is used for analyzing the uniform distribution condition of cement particles in the three-dimensional cement particle throwing area after the three-dimensional cement particle throwing is finished, and the division form of the analysis area comprises 2-4 horizontal division and vertical division analysis areas.
The method has the outstanding advantages that each group of proper cement particles is selected according to the range of the distribution characteristic value of the particle size of the cement particles, each group of particles represents the average fineness of the whole cement system, and the defect that the particles with smaller particle sizes at the last stage of throwing cannot be continuously thrown because the particles with larger particle sizes occupy too many vacant positions due to the excessively large particle sizes of the particles with larger particle sizes in the middle of a throwing area caused by a traditional random throwing method is overcome, so that the cement particles are uniformly distributed in the whole throwing area.
Drawings
Fig. 1 is a schematic diagram of the division of the cement particle placement analysis area according to the present invention.
Detailed Description
In order to make the purpose and technical solution of the present invention clearer, the following will clearly and completely describe the technical solution of the present invention with reference to the embodiments of the present invention.
Example (b):
the embodiment is a specific example of a three-dimensional grouping homogenization feeding method for cement-based material particles, and comprises the following steps:
step 1: generation of cement particle libraries
It is determined that the cement-based material particles to be numerically simulated in this example are PII 52.5 type portland cement produced by south beijing south of the Yangtze river-small-field cement limited, and the actual particle size distribution information of the cement measured by a laser particle size analyzer is shown in columns 1 and 2 in table 1. The simulated cement particle three-dimensional grouping homogenization feeding method in the embodiment is based on a cube feeding system with spherical cement particles, a water-cement ratio of w/c and a whole feeding area of 100um, and the smallest unit in the feeding area is a cube pixel with the side length of 1um, so that cement and water occupy 106The space of each pixel, the number of the pixels occupied by the cement, namely 1/(1+ rho)c(w/c)). times.1000000. Then, the number of cement particles of each particle size can be determined according to the corresponding cube pixel relationship (spherical particles with different radii occupy different numbers of cube pixels) contained in the spherical particles. When the water cement ratio was set to 0.6, concrete information before the particles were thrown is shown in table 1, and a cement particle library was created based on the concrete information, and 13 groups of particles having different radii were counted, and 3892 particles were counted.
Step 2: obtaining of cement particle size distribution characteristic value A and characteristic value range Z
According to the cement particle information obtained in the step 1, dividing the cement particles into three groups of particles with the radius larger than or equal to 1um, 4um and 8um, and calculating according to a formula (1) to obtain a particle size distribution characteristic value A:
in the formula, A is a cement particle size distribution characteristic value, A1、A4、A8Respectively the radius of the cement particles in the particle size distribution is more than or equal to 1um, more than or equal to 4um and more than or equal to 8umThe number of particles is a percentage of the total number of particles. Find A1＝1，A4＝0.04，A80.005, 1.04 and (0.64, 1.44) Z.
And step 3: grouped cement particle throwing
Randomly selecting 1 group from 13 groups of particles with different particle sizes by adopting uniform random numbers, selecting 1 particle in each group, continuously selecting 100 times, taking 100 particles as one group in total, calculating the A value of the 100 particles, and randomly throwing the 100 particles in a throwing area if the A value is in the particle size distribution characteristic value range Z; and if the value A is not in the particle size distribution characteristic value range Z, randomly selecting 100 particles again, and not starting to put the particles until the value A is in the particle size distribution characteristic value range Z. The total of 38 shots was made, and finally 92 pellets were left for a single shot, each shot having a value of A as shown in Table 2.
And 4, step 4: particle distribution condition analysis of three-dimensional cement particle putting area
The cement particle placement area of 100um x 100um was equally divided into upper and lower layers, each layer was equally divided into 9 zones, the lowest layer was zone 1 to zone 9, the uppermost layer was zone 10 to zone 18, and a total of 18 analysis zones were shown in fig. 1. The number of cement particles contained in each zone and the number of cement particles with different radii are counted and plotted into a table, as shown in table 3.
TABLE 1 Cement granule Release information
TABLE 2A value statistics
| 1.4 | 1.4 | 1.3 | 1.1 | 1.1 | 1.1 | 1.1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
TABLE 3 Cement particle distribution information
Comparative example:
the embodiment is a specific example of cement-based material particles which are thrown in the order of the radius from large to small, and comprises the following steps:
step 1 is the same as step 1 in example 1;
step 2: placing cement particles
And putting the cement particles in the cement particle library in the whole putting area according to the sequence of the radius from large to small, and randomly generating a putting position each time. When the next granule is dosed, there must not be an overlap with the area occupied by the previously dosed granule.
And step 3: particle distribution condition analysis of three-dimensional cement particle putting area
The cement particle throwing area of 100um is divided into upper and lower layers, each layer is divided into 9 areas on average, and the total number is 18 areas. The number of cement particles contained in each zone and the number of cement particles with different radii are counted and plotted into a table, as shown in table 4.
TABLE 4 Cement particle distribution information
Comparing table 3 with table 4, it can be calculated that, by adopting the grouping homogenization feeding method, the variance of the number of particles contained in 18 analysis areas after feeding is 17.8, the difference is 59 at most, and cement particles with the radius larger than or equal to 8um account for 47.4% in the second layer; the feeding method according to the radius is adopted, the variance of the number of the particles contained in 18 analysis areas after feeding is 22.5, the difference is 83 at most, and the cement particles with the radius larger than or equal to 8um account for 63.2 percent in the second layer. Therefore, the cement particles can be uniformly distributed in the whole target putting area by adopting the method for putting the cement particles, and the effectiveness and the reasonability of the method are proved.
Claims (5)
1. A cement-based material three-dimensional particle grouping and homogenizing throwing method is characterized by comprising the following steps:
step 1: establishing a cement particle library to be put
Determining the shape of cement particles and the particle size distribution information of the cement particles, drawing up the water cement ratio of the cement particles to be put in and the volume of a putting area, determining the total volume occupied by the cement particles according to the volume of the putting area and the water cement ratio, and further combining the shape of the cement particles and the particle size distribution information to generate a cement particle library to obtain N groups of cement particle sizes, wherein the number of the particles in each group is N;
step 2: obtaining a characteristic value A and a characteristic value range Z of the particle size distribution of cement particles
According to the cement particle library obtained in the step 1, calculating to obtain a particle size distribution characteristic value in the cement particle library, wherein the formula is as follows:
in the formula, A isCharacteristic value of particle size distribution of cement particles, A1、A4、A8The percentage of the number of particles with the particle diameter of more than or equal to 3um, more than or equal to 9um and more than or equal to 17um in the cement particle size distribution to the total number of particles, namely the percentage of the number of particles with the radius of more than or equal to 1um, more than or equal to 4um and more than or equal to 8um to the total number of particles, and the characteristic value range of the particle size distribution can be selected as Z (A-0.4, A +0.4) according to A;
and step 3: grouped cement particle throwing
Randomly selecting 1 group from N groups of particles with different particle sizes by adopting uniform random numbers, selecting 1 particle from the group each time, continuously selecting 100 times, taking 100 particles as a group in total, calculating the A value of the 100 particles, and randomly throwing the 100 particles in a throwing area if the A value is in a particle size distribution characteristic value range Z; and if the value A is not in the particle size distribution characteristic value range Z, randomly selecting 100 particles again, and not starting to put the particles until the value A is in the particle size distribution characteristic value range Z.
2. The method for uniformly distributing and feeding the cement-based material in groups of three-dimensional particles according to claim 1, wherein the particles in the step 1 are spheres, the particle size distribution information of the cement particles is measured by a laser particle size analyzer, the water-cement ratio is determined by a simulated cement particle system, and a feeding area is a cube with a volume of 100um by 100 um.
3. The method for uniformly distributing the cement-based material in groups according to claim 2, wherein in step 2, the minimum unit size of the cement-based material in the distribution area is 1um by 1um, and the particle size of the cement particles is 2+ 1.
4. The method of claim 3, wherein in step 3, after 100 particles satisfying the particle size distribution characteristic value range Z are selected, when the particles are randomly thrown in the throwing area, after the first particle is thrown, the position of the center of the sphere of the particle is fixed, and when the next particle is thrown, the position of the sphere of the particle is not overlapped with the position of the previously thrown particle, and if the position of the sphere of the first particle is overlapped with the position of the previously thrown particle, the positions of the other particles are randomly found until the positions of the other particles are not overlapped.
5. The method for uniformly distributing the cement-based material in groups according to claim 4, wherein the step 3 is followed by the steps of:
and 4, step 4: analysis of distribution condition of cement particle throwing area
Dividing a cement particle three-dimensional putting area into different distribution analysis areas, analyzing the distribution of cement particles contained in each area, drawing a table, and listing the content of cement particles in each distribution analysis area; the particle distribution analysis area is used for analyzing the uniform distribution of particles in the placement area after the cement particles are placed, the division form of the analysis area comprises transverse division and vertical division, and the number of the analysis areas is 2-4.
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